package org.yaosheng.algorithm.Data_Structures;

/**
 * Created by yaosheng on 2022/6/11.
 */
public class Array<E> {

    private E[] data;
    private int size;

    // 构造函数，传入数组的容量capacity构造Array
    public Array(int capacity){
        data = (E[])new Object[capacity];
        size = 0;
    }

    public Array(E[] arr){
        data = (E[])new Object[arr.length];
        for(int i = 0;i < arr.length;i ++)
            data[i] = arr[i];
        size = arr.length;
    }

    // 无参数构造函数，默认数组容量capacity=10
    public Array(){
        this(10);
    }

    // 获取数组中元素的个数
    public int getSize(){
        return size;
    }

    // 获取数组的容量
    public int getCapacity(){
        return data.length;
    }

    // 判断数组是否为空
    public boolean isEmpty(){
        return size == 0;
    }

    // 向所有元素后添加一个新元素
    public void addLast(E e){
        add (size,e);
    }

    public void addFirst(E e){
        add (0,e);
    }

    // 在第index位置插入一个新元素e
    public void add(int index,E e){

        if(index < 0 || index > size)
            throw new IllegalArgumentException ("Add Failed. Require index >=0 and index <= size");

        if(size == data.length)
            resize (2 * data.length);

        for(int i = size - 1;i >= index;i --)
            data[i + 1] = data[i];

        data[index] = e;
        size ++;
    }

    // 获取index位置的元素
    public E get(int index){
        if(index < 0 || index >= size)
            throw new IllegalArgumentException ("Get failed. Index is illegal");
        return data[index];
    }

    public E getLast(){
        return get (size - 1);
    }

    public E getFirst(){
        return get (0);
    }

    // 修改index位置的元素为e
    public void set(int index,E e){
        if(index < 0 || index >= size)
            throw new IllegalArgumentException ("Set failed. Index is illegal");
        data[index] = e;
    }

    // 查找数组中是否存在元素e
    public boolean contains(E e){
        for(int i = 0;i < size;i ++){
            if(data[i].equals (e))
                return true;
        }
        return false;
    }

    // 查找数组中元素e所在的索引，如果不存在，则返回-1
    public int find(E e){
        for(int i = 0;i < size;i ++){
            if(data[i].equals (e))
                return i;
        }
        return -1;
    }

    // 从数组中删除index位置的元素，返回删除的元素
    public E remove(int index){
        if(index < 0 || index >= size)
            throw new IllegalArgumentException ("Remove failed. Index is illegal");
        E ret = data[index];
        for(int i = index + 1;i < size;i ++)
            data[i - 1] = data[i];
        size --;
        data[size] = null;   // 进行gc

        // 当数组元素达到数组长度四分之一时，对数组进行缩容
        if(size == data.length / 4)
            resize (data.length / 2);
        return ret;
    }

    // 从数组中删除第一个元素，返回删除的元素
    public E removeFirst(){
        return remove (0);
    }

    // 从数组中删除最后一个元素，返回删除的元素
    public E removeLast(){
        return remove (size - 1);
    }

    // 从数组中删除元素e
    public void removeElement(E e){
        int index = find (e);
        if(index != -1)
            remove (index);
    }

    public void swap(int i,int j){

        if(i < 0 || i >= size || j < 0 || j >= size){
            throw new IllegalArgumentException ("Index is illegal.");
        }
        E t = data[i];
        data[i] = data[j];
        data[j] = t;
    }

    @Override
    public String toString(){

        StringBuilder res = new StringBuilder ();
        res.append (String.format ("Array: size = %d, capacity = %d\n",size, data.length));
        res.append ('[');
        for(int i = 0;i < size;i ++){
            res.append (data[i]);
            if(i != size - 1)
                res.append (", ");
        }
        res.append (']');
        return res.toString ();
    }

    // 数组扩容
    private void resize(int newCapacity){
        E[] newData = (E[])new Object[newCapacity];
        for(int i = 0;i < size;i ++)
            newData[i] = data[i];
        data = newData;
    }
}
